Parkinson’s disease is a common neurodegenerative disease affecting the movement and well-being of most elderly. The manifestations of Parkinson’s disease often include resting tremor, stiffness, bradykinesia, and muscular rigidity. The typical hallmark of Parkinson’s disease is the destruction of neurons in the substantia nigra and the presence of Lewy bodies in different compartments of the central nervous system. Due to various limitations to the currently available treatments, immunotherapies have emerged to be the new approach to Parkinson’s disease treatment. This approach shows some positive outcomes on the efficacy by removing the aggregated species of alpha-synuclein, which is believed to be one of the causes of Parkinson’s disease. In this review, an overview of how alpha-synuclein contributes to Parkinson’s disease and the effects of a few new immunotherapeutic treatments, including BIIB054 (cinpanemab), MEDI1341, AFFITOPE, and PRX002 (prasinezumab) that are currently under clinical development, will be discussed.